Avocado

24.05.17

Overview

The avocado (Persea americana) is a tree native to Mexico and Central America. It produces a pear shaped fruit with firm skin and soft, creamy, buttery flavoured, pale green flesh. Nutrient rich, cholesterol free and containing poly and monounsaturated (“good”) fats, avocados are a popular ingredient in savoury dishes, including salads, sandwiches and dips.

The avocado tree is evergreen and grown in tropical, subtropical and Mediterranean climates throughout the world. While there is some evidence, including cave paintings and pottery fragments, that avocados may have been cultivated for thousands of years, records of the fruit date back to the early 1500s when the Spanish conquistadors discovered the avocado being widely cultivated in South America.

In Australia production is widespread, which results in year-round supply, but the major production regions are the Atherton Tablelands and around Bundaberg in Queensland and the south west of Western Australia. While avocado trees are adaptable to a range of climates, they are frost susceptible, particularly when young, so they are best suited to frost-free locations.

As for all tree crops, new entrants to the avocado industry will carry the risk related to the length of time between planting and the first commercial harvest, which for avocado is approximately three years.

Avocados were first planted in Australia in the 1840s, but the commercial industry only dates back to the late 1960s and is small by global standards. As at 2012–13, the Australian avocado industry consisted of around 850 growers, who produced 54,877 tonnes of avocados.

The Australian avocado industry is well organised with established markets, research and development undertaken by Horticulture Australia Limited and an active industry peak body, Avocados Australia.

Facts and figures

  • The avocado is a tree native to Mexico and Central America
  • As at 2012–13 there were 850 avocado growers in Australia producing almost 55,000 tonnes
  • Avocados are adaptable trees and can be grown in a range of (frost free) climates across Australia
  • Avocado trees will need supplementary irrigation all year, regardless of climate
  • Avocado trees are susceptible to phytophthora root rot, a devastating disease that can kill trees
  • The first commercial-sized avocado crop should be harvested three years after planting
  • Avocados are harvested by hand and can be easily damaged, decreasing marketability

Production status

In 2012–13, approximately 850 growers produced 54,877 tonnes of avocados in Australia.

Due to the avocado tree’s climate adaptability, the industry is spread across Australia, ensuring year round supply. Avocado production takes place in the north and south of Western Australia, the TriState region (the irrigated regions of the lower Murray Valley where the borders of New South Wales, Victoria and South Australia meet), central and northern coastal New South Wales, and south east and central coastal regions and Atherton Tablelands of Queensland.

Map of potential and current growing regions

Uses

Avocados are most commonly eaten as a fresh food on their own. They are a popular accompaniment to meat and seafood dishes, and used as an ingredient of savoury foods, including salads, sandwiches and dips. Avocado can also be used in ice-cream and milkshakes. Avocado oil can be used in cooking and has some beauty applications including bath oil and massage oil.

Avocados are rich in fibre and monounsaturated (good) fats, while naturally low in sugar and sodium. Avocados are also nutrient rich and contain many essential vitamins and minerals.

Production Requirements

Growing regions

Avocados are grown in three climate zones in Australia, and within these, the key growing regions are:

  • tropical – Atherton Tablelands/Mareeba
  • subtropical – Bundaberg and Burnett regions in Queensland, south east Queensland and north coast of New South Wales
  • Mediterranean – Riverland (South Australia), Sunraysia (Victoria/New South Wales) and south west Western Australia (Pemberton and Perth).

Soil type

Ideally, avocados should be grown in a rich sandy loam with a soil pH(CaCl2) of 5.5–6.5. Light sandy soils will need to be enriched with organic matter before planting. However, with suitable management techniques, avocados can be grown in a range of soil types from light sands through to well-drained clays.

The main requirement for avocado production is to ensure the soil is free draining and of a good depth—preferably over two metres but at least 1m—to avoid waterlogging and mitigate infection by root rot pathogens. Where necessary, soil mounding can be used to improve soil depth and drainage.

Soils must not be salt affected and soil chloride levels should ideally be under 150 mg/kg.

Climate

Avocado trees are adaptable to a range of climates, and grow commercially from tropical regions in Queensland to Mediterranean regions of Victoria and Western Australia, and subtropical regions in between. However, careful attention should be paid to the micro-climate as trees are susceptible to frost, particularly when young, as well as wind, sunburn and salt spray.

In commercial orchards, irrigation will be required in addition to natural rainfall. Avocados are shallow rooted trees and are easily water stressed, affecting fruit production and quality. Further, as an evergreen tree, water requirements extend throughout the year, and irrigation may be required after harvest during dry spells in winter, in some regions.

Varieties

Different varieties suit different growing regions. The main varieties of avocado grown in Australia are Hass, Shepard, Reed, Sharwil and Wurtz. Hass is the dominant variety globally and in Australia represents about 80% of production while Shepard represents about 10% of production (at 2012–13).

Hass avocados are known for their oval shape and pebbly skin that turns dark purple-black when ripe. Due to its adaptability to a range of growing regions, Hass avocados are available for most of the year, however Hass does not grow very well in the more tropical locations

Shepard avocados have a smooth green, glossy skin with a longer neck than the Hass. The flesh has a mild, buttery flavour and doesn’t turn brown when cut. Shepard is available in peak supply from February to April. It requires a more tropical climate.

Only known varieties of avocado should be grown commercially. Because avocado trees do not grow true to type from seed, commercial orchards should be established from grafted trees, where a preferred variety is transplanted (grafted) onto rootstock.

Planting and crop management

Site selection for avocado plantings is very important and careful attention should be paid to the micro-climate of the site, as trees are susceptible to frost (particularly when young), wind, sunburn and salt spray.

Windbreak protection is essential. At the very least, windbreaks should be placed along the edge of the orchard at right angles to the prevailing winds. Many growers also include internal windbreaks every 100 to 200m within the orchard. These windbreaks should be established prior to planting the avocado trees.

To protect from sun damage, it may be necessary to paint the young trees’ bark with white acrylic paint and mulch should be incorporated into the soil at planting to act as insulation. Young trees can also be damaged by herbicide over spray and the use of protective tree trunk guards is also recommended.

A soil test should be conducted well before planting so soil pH and nutrient levels can be corrected, noting that it may take longer than one year to correct a soil nutrient imbalance.

Site selection should also consider good drainage as avocados are extremely susceptible to the phytophthora root rot and no avocado rootstock is completely resistant to this disease. Water should not pool on the surface for more than 24 hours and there should be good drainage through the soil profile to at least 1m (preferably more). While sloping land will aid drainage, steep gradients will make harvesting and other management operations difficult. Steep sites are also susceptible to erosion.

Trees should be sourced from a specialist nursery because avocado trees do not grow true to type from seed. Commercial orchards should be established using grafted trees—where a preferred variety is transplanted (grafted) onto rootstock. The industry group Avocados Australia can provide information about reputable suppliers.

Avocados are evergreen, therefore they can be planted at almost any time of the year. Planting holes should be large enough to take the root system comfortably but large holes are unnecessary. Ensure the soil is well broken up on the sides to prevent roots spiralling in the tree hole. Do not place fertilisers in the planting hole, as they can burn young tree roots.

Avocado trees can grow quite large (up to 20m) if canopy size is not managed, so row spacing is important. Spacings of 12 x 6m, 10 x 5m, and 8 x 4m (equivalent to 138–312 trees per hectare) are popular. Generally rows should run north–south to allow better infiltration of sunlight.

Pruning of new plantings is not required as avocado trees generally shape themselves. However, in order to create a bushier, more compact tree that is easier to manage, strong upward growing tips should be pinched out to promote side shoots during the first two years of growth. Any branches causing overcrowding and shoots from below the grafted area should be removed. As they grow, trees will require regular pruning to manage the canopy size and fruiting capacity.

Fertiliser rates will depend on a range of factors, including tree size, variety, soil type and irrigation. It is recommended that leaf analysis be undertaken in order to identify fertiliser needs. The New South Wales Department of Primary Industries Avocado Growing Guide includes detailed information on fertiliser needs.

An important point to remember is that avocado trees are evergreen and in most regions will require irrigation all year, including dry spells during winter. They are very sensitive to moisture stress, especially during flowering, fruit set and fruit development. During these critical periods the soil profile should be monitored to ensure it does not dry out. Annual supplementary water needs vary with region, from 3–5ML/ha in subtropical regions to 12–15ML/ha in Mediterranean regions.

Weeds, pests, and diseases

Weeds compete with newly planted trees for water and nutrients, therefore weed control before planting is important, as is mulching of the rows after planting. In a well-maintained mature orchard, the inter-row area is mown regularly to assist access to the trees and planting rows are mulched or sprayed with herbicide to minimise weeds.

Avocado is susceptible to a number of pests and diseases, whose distribution is influenced largely by climate. State departments of agriculture provide information on pests and diseases, and their management, see Pests and diseases of avocados (Queensland) and Avocado Diseases (New South Wales) for more detailed information.

The most serious disease of avocado is phytophthora root rot, which can kill trees, and is caused by the soil-borne fungus Phytophthora cinnamomi Rands. It is a particular risk to trees that are sited in poorly drained soils.

Present in nearly all Australian orchards, root rot control is an ongoing management task for horticulturalists. As its name suggests, root rot destroys the root systems of trees and inhibits their ability to take up sufficient water or nutrients. Effective control of the disease involves good horticultural practice and an integrated management, which includes effective drainage, mulching, appropriate irrigation management, fungicide treatment and suitable soil pH of about 5.5.

Plant Health Australia has developed an Orchard Biosecurity Manual for the avocado industry.

Infrastructure Requirements

The infrastructure on most established horticultural enterprises will suit avocado production. This includes irrigation, as well as cleaning, sorting, packing and refrigeration/cooling infrastructure.

If growing avocado in high wind areas, windbreaks will need to be built or planted.

Avocado is usually harvested by hand using ladders, cherry pickers and picking poles. Hydraulically operated platforms may be used on flat country.

If starting a new horticultural enterprise, the infrastructure needed may include:

  • tractor
  • irrigation system
  • spray equipment with separate spray units for pesticides and herbicides
  • slasher or mower
  • trailer and farm vehicle
  • farm shed
  • harvesting equipment (ladders, secateurs, bins)
  • cool room
  • sorting/grading and packing equipment (scales)
  • pruning equipment.

Harvesting & Processing

Avocado will mature on the tree but the fruit will not ripen until harvested. The dull appearance of the skin and shrivelling and yellowing of the fruit stalk will indicate fruit maturity. As well, when a mature avocado is cut open the seed coat is dark brown and dry, and does not stick to the flesh.

Fruit maturation can occur over 4–6 weeks, so several pickings are recommended. The largest fruit should be harvested in the first picking. Avocados are hand harvested using ladders and picking poles. Hydraulically operated platforms and cherry pickers can be used on flat country.

Bruising and body rots are the major post harvest problems and severely diminish an avocado’s market value. Therefore it is important to ensure avocados are not dropped or pierced by fingernails and that the flesh is not torn around the stem as the fruit is picked, as this provides a site for potential infection.

Harvested avocados should be placed in the shade until the fruit is returned to the packing house, and a fungicide should be applied within 24 hours of harvest to control anthracnose and stem-end rot.

Storing at the correct temperature and appropriate handling will maintain the quality of harvested avocados. Fruit will need to be cooled below 20°C within 24 hours after harvesting, if this is not done the ripening phase will be triggered.

Avocados are usually packed into plastic trays, with moulded-cup inserts to protect the fruit, which hold 12–28 fruit. Smaller fruit are bulk packed into 10kg cartons.

Avocados Australia has developed a Ripening ManualMaturing Monitoring information and handling information to assist everyone along the supply chain to ensure the best quality avocados reach the consumer.

Although trees may start to bear fruit in the second year, commercial quantities are generally not harvested until the third year. It is also important to remember that avocado’s have a biennial or alternate yielding pattern, where yields alternate from high in one year to low yields the next. For more detailed information refer to Avocados Australia’s information on biennial or alternative yielding.

As at 2010, the average yield of avocados across Australian orchards was nine tonnes per hectare, reflecting variable genetic performance of seedling rootstocks and difficulties in properly managing phytophthora root rot. However with high level management, including good control of root rot and orchards based on good rootstock, yields of 20 t/ha can be achieved.

Markets and Marketing

Most avocados are sold to wholesale markets in the capital cities, however some larger growers sell directly to major supermarkets or alternatively sell to packers or agents who consolidate produce from a number of growers to ensure consistent supply to a supermarket. Smaller growers may sell at farmers markets or at roadside stalls. Where high quality infrastructure and transport services exist, fresh Australian avocados can be air-freighted to Asian markets in premium condition.

When planning to market any horticultural product, it is important to remember that wholesalers and retailers are generally looking for the following attributes from a supplier:

  • a great tasting product
  • high quality flesh texture
  • ·on-time delivery and consistency of supply.

Avocados Australia runs a Quality Program that provides insights into consumer expectations of avocado quality.

The horticultural supply chain provides a useful framework for industry entrants to understand the potential marketing structure. A typical supply chain for horticultural production has the following linkages:

  • grower
  • packer
  • transporter
  • unloading agent
  • wholesaler/agent
  • (potentially a secondary wholesaler)
  • processor
  • exporter
  • retailer
    • chain retailer (e.g. major supermarket)
    • specialist retailer (e.g. a fruit and vegetable shop)
    • foodservice (e.g. a restaurant)
  • consumer.

These are not necessarily listed as a sequential supply chain, for example some growers will bypass packers and wholesalers and sell directly to restaurants or consumers. Wholesalers will also sell to secondary wholesalers, who in turn on-sell to smaller retail buyers and providores who may supply the food service industry.

Price may be affected by seasonal availability, the availability of substitute products and consumer spending and preferences. Premium produce will generally earn a premium price, however, there are no guarantees of this always happening. For example an oversupply of high quality fruit will depress prices but equally, periods of low availability will see even average quality fruit command high prices.

One of the best ways to monitor price signals and plan production accordingly is for the producer to establish a good business relationship with the wholesaler/agent. This can add some transparency around market signals.

Since September 2008, Avocados Australia has been collecting weekly retail prices from 64 stores in capital cities including Brisbane (Qld), Sydney (NSW), Melbourne (Vic) and Perth (WA). Understanding the retail price for avocados will assist growers determine their supply chain efficiencies. The retail prices are available on theAvocados Australia website.

Avocados Australia also provides extensive and timely information through Infocado which reports on the movement of avocados through the supply chain in order to assist grower packers make more informed management and marketing decisions.

Risks and Regulations

Risks/challenges

Like all tree crops, the biggest commercial risk to new entrants to the industry is the length of time between planting and the first commercial harvest (approximately three years). Add to this that new orchards may require significant upfront investment (for example, irrigation systems), intensive management and a significant investment of time and energy, a return on investment may take quite a number of years.

Other risks associated with growing avocado may include:

  • unpredictable weather conditions affecting yield, meaning inconsistent cropping from year to year
  • crop losses from pests or diseases (or vermin, including rats if located near waterways)
  • the availability and cost of labour, as avocado are harvested by hand
  • the relatively short amount of time to transport fruit to market before it starts to deteriorate
  • the lack of understanding of wholesalers and retailers in how to handle the fruit to prevent bruising, which may result in lower prices or wastage.

Regulatory considerations

The standard regulatory considerations that apply to all Australian farms, including laws applying to chemical use and management, occupational health and safety and transport (including machinery movements and the loading/unloading of harvested product), apply to avocado operations.

Publications

Publications/ information products

Avocado Industry Strategic Plan 2011- 2015  Horticulture Australia Ltd

Avocado industry annual investment plan  Horticulture Australia Ltd

Avocado industry annual reports  Horticulture Australia Ltd

Avocado Horticulture Australia Ltd Fact Sheet (2012)

Avocado culture in WA  Department of Agriculture and Food Western Australia Bulletin (2006)

Avocado maturity testing  Department of Agriculture and Food Western Australia Farmnote (2007)

Avocado – grading and packing standard guidelines  Department of Agriculture and Food Western Australia Farmnote (2006)

Avocados – new woolbelt opportunities  Department of Agriculture and Food Western Australia brochure (2008)

Avocado Levy  Australian Government Department of Agriculture (2013)

Avocado Diseases  New South Wales Department of Primary Industries (2004)

Retail pricing  Avocados Australia

Infocado  Avocados Australia

Qualicado  Avocados Australia

Avocado Growing  New South Wales Department of Primary Industries (2003)

Other resources

Avocados in Western Australia – overview  Department of Agriculture and Food Western Australia

Avocado  Horticulture Australia Ltd

Avocados  Queensland Department of Agriculture, Fisheries and Forestry

Talking Avocados Industry Magazine

Avocadosource  free, virtual library of avocado knowledge

Image Gallery

Avocado under cultivation (source Avocados Australia)

Hass avocado on the tree (source Avocados Australia)